Sex and gender differences in autism

This article's lead section may be too long. Please read the length guidelines and help move details into the article's body. (June 2023)

Sex and gender differences in autism exist regarding prevalence, presentation, and diagnosis.

Men and boys are more frequently diagnosed with autism than women and girls. It is debated whether this is due to a sex difference in rates of autism spectrum disorders (ASD) or whether females are underdiagnosed.^[1][2] The prevalence ratio is often cited as about 4 males for every 1 female diagnosed.^[3] Other research indicates that it is closer to 3:1 or 2:1.^[2][4] One in every 42 males and one in 189 females in the United States is diagnosed with autism spectrum disorder.^[5] There is some evidence that females may also receive diagnoses somewhat later than males; however, thus far results have been contradictory.^[6]

Several theories exist to explain the sex-based discrepancy, such as a genetic protective effect,^[7][8][9] the extreme male brain theory^[10][11][12] and phenotypic differences in the presentation between sexes,^{[9][13][14][15]} which may all be intertwined. Researchers have also debated whether a diagnostic gender bias has played a role in females being underdiagnosed with autism spectrum disorder.^[16] Researchers have also speculated a gender bias in parental reporting due to the expectations and socialization of gender roles in society.^[17]

Since autism is a largely genetic and hereditary condition, genetic factors that lead to differences depending on sex come into play, such as the role of androgen signaling in male development or X-linked mutations, whose associated genetic conditions are typically more common and severe in males. The extreme male brain theory suggests that autistic brains show an exaggeration of the features associated with male brains, such as increased size and decreased relative connectivity as well as systematic thinking over empathetic thinking.^[18] The imprinted brain hypothesis suggests genomic imprinting is at least partly responsible for the sex differences in autism and points to the evidence for a common genetic cause with schizophrenia.^[19][20][21]

Compared to men, women are generally required to be more impaired by their autism^[22] or have more cognitive or behavioral conditions^[23] than their male counterparts to meet autism spectrum criteria. There is evidence of increased incidence of social anxiety,^[14] anorexia nervosa^[24][25] and self-harm in autistic females,^[26] though the increased rates of anorexia nervosa and other eating disorders^[27] may be due to confusion or conflation with avoidant/restrictive food intake disorder (ARFID), which is particularly common in autism.^[28] Autistic girls and women show higher social motivation and a greater capacity for typical friendships than autistic boys and men,^[29][30] are less likely to be hyperactive, impulsive, have issues with conduct or stereotyped behavioral traits,^[31][32] and have been shown to mask their autistic behaviors and social difficulties more frequently than autistic men.^[33] Autistic males often exhibit more easily observed behaviors at a younger age resulting in parental observance and subsequent evaluation of the child. In contrast, behavior of young females is more often overlooked, regardless of any associated at-risk factors^{[broken anchor]} for ASD or other developmental delays. Ultimately, this may contribute to females more frequently receiving their ASD diagnosis later in life than their male counterpart.^[34] There is a growing consensus among neuroscientists that the number of autistic women has been vastly underrepresented due to the assumption that it is primarily a male condition.^[35]